1. Field of the Invention
This invention relates to components for wear-resistant surfacing of metal screw conveyors, particularly conveyors of centrifuges, and to such conveyors surfaced therewith.
2. Description of the Prior Art
U.S. patent application of Elwin Lewoczko, Ser. No. 533,198, filed Dec. 16, 1974, assigned to the assignee of the present application, discloses a screw conveyor for centrifuges in which segments of wear-resistant surfacing material are secured to a helical metal stub blade against radial outward and axial movements under high centrifugal forces, by slidably interlocked mating parts on the segments and the blades. The conveyor of the aforesaid application is a substantial improvement over wear-resistant surfaced conveyors of the prior art in both retention of the segments under high centrifugal forces and ease of replacement of worn segments in the field.
However, the embodiment of the invention disclosed in the aforesaid application utilizes a wedge-shaped projection on the blade face of the segments and wedge-shaped pieces on the blade as the mating parts which form a dovetail joint when the segment is slid radially outwardly on the blade to wedge the projection edges under the edges of the wedge-shaped pieces. In this arrangement, disassembly of a worn segment requires that it be slid radially inwardly to disengage the mating parts, which would not be possible as to any segment between others if all segments had the usual shape, diminishing in width from outer to inner ends to compensate for the diminishing radius of curvature of the helix toward their inner ends. The arrangement of the aforesaid application makes such disassembly possible by providing two different shapes of segments which are used in alternation, which works satisfactorily but complicates somewhat the molding of segments, their assembly to the conveyor and the stocking of spare parts.